1. Field of the Invention
The present invention relates to a projection type display apparatus which comprises unnecessary polarized light removing means for each color light which removes an unnecessary polarized component with respect to image light of each color emitted from a reflective spatial light modulation element (a reflective liquid crystal panel) for each color light corresponding to each of R light, G right and B light, and also comprises air-cooling means for air-cooling the unnecessary polarized light removing means for each color light.
2. Description of the Related Art
Although a projection type display apparatus which magnifies and projects a color image has various kinds of structural conformations depending on arrangement relationships of optical constituent members, there are a transmission type which allows light to be transmitted through a spatial light modulation element (which will be referred to as a liquid crystal panel hereinafter) using a liquid crystal panel or the like and a reflection type which reflects light. In both of these types, white light emitted from a light source is divided based on each color into three primary color lights, i.e., R light (red light), G light (green light) and B light (blue light) by a color separation optical system, the three primary color lights are respectively led to liquid crystal panels for the R, G and B lights, the respective image lights of the R light, the G light and the B light subjected to light modulation in accordance with respective image signals for the R, G and B lights in the respective liquid crystal panels for the R, G and B lights are subjected to color combination by a color combination optical system, and color-combined image light acquired by the color combination optical system is magnified and projected onto a screen from a projection lens.
At this time, there has been proposed a projection type display apparatus having a configuration in which, when a quantity of the lights which enter a polarizer and a liquid crystal panel is increased in order to increase luminance of the projected color-combined image light in the projection type display apparatus, the polarizer and the liquid crystal panel generate heat, but the polarizer and the liquid crystal panel are cooled by supplying cooling air in substantially parallel with respective surfaces of the polarizer and the liquid crystal panel, thereby projecting the color-combined image light with higher luminance onto the screen (see, e.g., Japanese Patent Application Laid-open No. 2000-194073).
FIG. 1 is a structural view showing a conventional projection type display apparatus. FIG. 2 is a side view showing an arrangement of cooling fans in the conventional projection type display apparatus. FIG. 3 is a perspective view showing a state in which a polarizer and a liquid crystal panel are cooled in the conventional projection type display apparatus.
A projection type display apparatus 200 according to the prior art shown in FIG. 1 is disclosed in the above-described Japanese Patent Application Laid-open No. 2000-194073, and will be briefly described herein with reference to documents.
As shown in FIG. 1, in the conventional projection type display apparatus 200, a parallel light ray emitted from a non-polarized light source 202 provided in a casing 201 is turned to visible light by a UV/IR cut filter 203, and this visible light is transmitted through and reflected by a first color separation dichroic mirror 204. Further, one color light transmitted through the first color separation dichroic mirror 204 travels forward to reach a reflecting mirror 205, and is reflected by this reflecting mirror 205 to change its direction 90°, and enters a first liquid crystal panel assembly 210A.
On the other hand, two color lights reflected by the first color separation dichroic mirror 204 change their directions 90° here to reach a second color separation dichroic mirror 206, and are transmitted through and reflected by this second color separation dichroic mirror 206. Furthermore, one color light reflected by the second dichroic mirror 206 of the two color lights changes its direction 90° to enter a second liquid crystal panel assembly 210B, and the other color light transmitted through the second color separation dichroic mirror 206 travels forward to enter a third liquid crystal panel assembly 210C.
Here, the first to third liquid crystal panel assemblies 210A to 210C corresponding to RGB are respectively constituted as a transmission type in which a condenser lens 211, a polarizer 212, a liquid crystal panel 213 and a polarizer 214 are sequentially arranged.
Moreover, one color light transmitted through the first liquid crystal panel assembly 210A is transmitted through a first color combination dichroic mirror 207 to enter a second color combination dichroic mirror 209 and, on the other hand, one color light transmitted through the second liquid crystal panel assembly 210B is reflected by the first color combination dichroic mirror 207 to enter the second color combination dichroic mirror 209, and the other color light transmitted through the third liquid crystal panel assembly 210C is reflected by a reflecting mirror 208 to enter the second color combination dichroic mirror 209. The three color lights are subjected to color combination by this second color combination dichroic mirror 209, and color-combined image light is magnified and projected onto a non-illustrated screen.
At this time, as shown in FIG. 2, there is a description in which fans 221A to 221C as cooling means are provided on an outer side surface of the casing 201 in accordance with the first to third liquid crystal panel assemblies 210A to 210C (FIG. 1). Additionally, an air stream from the fan 221A (221B, 221C) is supplied in a direction indicated by an arrow X and a direction indicated by an arrow Y in substantially parallel with respective surfaces of the polarizer 212 and the liquid crystal panel 213 in each of the first to third liquid crystal panels 210A (210B, 210C) through a fan duct 222A (222B, 222C), effective cooling can be thereby performed, and it is possible to obtain the projection type display apparatus 200 capable of projecting the color-combined image light having higher luminance onto a screen.
Meanwhile, according to the conventional projection type display apparatus 200, since each polarizer 212 and each liquid crystal panel 213 in the first to third liquid crystal panel assemblies 210A to 210C corresponding to RGB are respectively cooled by using the three fans 221A to 221C and the three fan ducts 22A to 222C, the three cooling means disadvantageously have a large-scaled structural conformation.
Additionally, the conventional projection type display apparatus 200 has each liquid crystal panel 213 for each of the R, G and B lights constituted as a transmission type, but acquisition of a high resolution with respect to a projected image is difficult in case of the transmission type. Thus, when a reflective liquid crystal panel is adopted in order to achieve the high resolution, even if the cooling means in the conventional projection type display apparatus 200 are used as they are, the cooling means likewise have a large-scaled structural conformation.